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Dr. Gina Semprebon, Chairman of the Science and Mathematics departments at Bay Path College, holds a skull made from the mold of "Lucy," which was found in Ethiopia in 1974 and is said to be 3.2 million years old. Lucy was the oldest, most complete skeleton found at the time and showed the earliest bi-ped ever found which still had a small brain. (STEPHEN DUNN / HARTFORD COURANT / October 7, 2009) |
From the fossilized teeth of ancient giraffes, antelopes and horses, scientist Gina Semprebon can begin to draw a prehistoric landscape. Tooth wear tells Semprebon what the animals of a region ate — whether they tore leaves from trees or chomped on grass. With the types of plants revealed and other evidence from fossils and soil, Semprebon and her fellow scientists can unfold a panorama of long-ago forests and fields, rivers that flowed and the climate that ruled a region's seasonal changes.
This is paleoecology, the study of ancient ecosystems. Semprebon, a biology professor at Bay Path College in Longmeadow, Mass., is widely known in the emerging field and was part of a recent study that changed the book on human evolution.
The Enfield resident was among scientists who investigated the world of Ardipithecus ramidus, or "Ardi," a 4.4-million-year-old hominid from Ethiopia. The investigators' results were published in the Oct. 2 issue of the journal Science.
Ardi is now the earliest-known skeleton from the human branch of the primates, eclipsing "Lucy" [Australopithecus afarensis], a female who also lived in northern Africa but more recently — about 3.2 million years ago.
Scientists found bones of at least 36 individuals from Ardi's species and thousands of fossilized remains of other animals and plants. They concluded that Ardi lived in a landscape dominated by woodlands, with freshwater springs, fig and hackberry trees, owls, porcupines, bears, pigs, land snails, elephants, horses, giraffes and other animals.
Ardi was relatively large for her species at 110 pounds. Her cranial capacity was a bit smaller than Lucy's and close to a chimpanzee's, according to researchers. Ardi lived in trees and on the ground, combining traits of the four-legged, mostly tree-dwelling apes and upright, mostly ground-dwelling humans.
Scientists say Ardi has brought us closer to an understanding of how human beings developed from the fork in the primate tree where chimpanzees and hominids split.
Last week, Semprebon answered questions about the Ardi investigation and what the discovery means.
Q: How did you get involved in this study?
A: My primary area of research has been dietary and habitat reconstruction of mammals. I present all over the world. I was approached after giving a talk at a conference in Austin, Texas, a couple of years ago.
Q: What was your role?
A: My part was to look at tooth morphology [scientific study of form and structure],primarily of the large mammals that lived in the same place as Ardi. ... I analyze the shape of the various parts of the tooth and I can tell right away if the animal was eating leaves from trees.
Q: What are the signs of that?
A: Very sharp cusps [elevations on the chewing surface] — the tips of the cusps are very sharp. It enables them to shear the leaves. Grass is a very abrasive food that wears the teeth into rounded and blunt cusps. ... I've examined many living animals today. We know what they ate; you have to have a modern reference.
Q: What kinds of tools do you use?
A: We look at them with the naked eye. We take a look at the shape. That tells you a lot about diet. The other way is to look at it under a microscope. You can see food scars. Different foods, different plants have substances that can pit and scratch the teeth.
We also look at the chemicals in the enamel, and that tells us what kinds of plants the animal ate when making its tooth enamel.
Q: Is paleoecology a new field?
A: Paleoecology is fairly new. We're looking at the animal. What was its behavior? Where did it live? We primarily focused on anatomy in the past; now we want to bring these organisms to life so we understand what these organisms were like when they were roaming the Earth.
Q: What attracted you to paleoecology?
A: I just love the idea of bringing prehistoric animals back to life. They weren't just bones; they were actual animals that lived in actual habitats.
Q: So when you learn what an ancient giraffe or antelope ate, where do you go from there?
A: We can reconstruct the type of environment: Was it dry? Humid? Also, was it a closed habitat like a forest, or was it open habitat? Those are the types of things we're looking for.
Q: What are the benefits of this research?
A: The research shows us our roots. ... It's kind of turned around our own ideas as to our roots. Up until this study, there has been an idea that we were pretty much forced out of the trees because we evolved in these open grasslands. That is a very common misperception.
[The Ardi investigation] really shows you that what we think of as a pretty unique human trait — bipedal locomotion — we didn't get pushed into this because we had to live in a grassland environment. We have to figure out another story.
Q: So we figure out how we came out of the trees — what do we learn from that?
A: If you take a look at the animal kingdom, how many animals are walking around on two legs? Obviously, understanding what caused us to do that gives us a better understanding of human beings. We're dominant on this planet. We've pretty much freed our hands to do things other than walking around on them ... and using our hands to manipulate objects like tools may have contributed to the expansion of the brain.
This is paleoecology, the study of ancient ecosystems. Semprebon, a biology professor at Bay Path College in Longmeadow, Mass., is widely known in the emerging field and was part of a recent study that changed the book on human evolution.
The Enfield resident was among scientists who investigated the world of Ardipithecus ramidus, or "Ardi," a 4.4-million-year-old hominid from Ethiopia. The investigators' results were published in the Oct. 2 issue of the journal Science.
Ardi is now the earliest-known skeleton from the human branch of the primates, eclipsing "Lucy" [Australopithecus afarensis], a female who also lived in northern Africa but more recently — about 3.2 million years ago.
Scientists found bones of at least 36 individuals from Ardi's species and thousands of fossilized remains of other animals and plants. They concluded that Ardi lived in a landscape dominated by woodlands, with freshwater springs, fig and hackberry trees, owls, porcupines, bears, pigs, land snails, elephants, horses, giraffes and other animals.
Ardi was relatively large for her species at 110 pounds. Her cranial capacity was a bit smaller than Lucy's and close to a chimpanzee's, according to researchers. Ardi lived in trees and on the ground, combining traits of the four-legged, mostly tree-dwelling apes and upright, mostly ground-dwelling humans.
Scientists say Ardi has brought us closer to an understanding of how human beings developed from the fork in the primate tree where chimpanzees and hominids split.
Last week, Semprebon answered questions about the Ardi investigation and what the discovery means.
Q: How did you get involved in this study?
A: My primary area of research has been dietary and habitat reconstruction of mammals. I present all over the world. I was approached after giving a talk at a conference in Austin, Texas, a couple of years ago.
Q: What was your role?
A: My part was to look at tooth morphology [scientific study of form and structure],primarily of the large mammals that lived in the same place as Ardi. ... I analyze the shape of the various parts of the tooth and I can tell right away if the animal was eating leaves from trees.
Q: What are the signs of that?
A: Very sharp cusps [elevations on the chewing surface] — the tips of the cusps are very sharp. It enables them to shear the leaves. Grass is a very abrasive food that wears the teeth into rounded and blunt cusps. ... I've examined many living animals today. We know what they ate; you have to have a modern reference.
Q: What kinds of tools do you use?
A: We look at them with the naked eye. We take a look at the shape. That tells you a lot about diet. The other way is to look at it under a microscope. You can see food scars. Different foods, different plants have substances that can pit and scratch the teeth.
We also look at the chemicals in the enamel, and that tells us what kinds of plants the animal ate when making its tooth enamel.
Q: Is paleoecology a new field?
A: Paleoecology is fairly new. We're looking at the animal. What was its behavior? Where did it live? We primarily focused on anatomy in the past; now we want to bring these organisms to life so we understand what these organisms were like when they were roaming the Earth.
Q: What attracted you to paleoecology?
A: I just love the idea of bringing prehistoric animals back to life. They weren't just bones; they were actual animals that lived in actual habitats.
Q: So when you learn what an ancient giraffe or antelope ate, where do you go from there?
A: We can reconstruct the type of environment: Was it dry? Humid? Also, was it a closed habitat like a forest, or was it open habitat? Those are the types of things we're looking for.
Q: What are the benefits of this research?
A: The research shows us our roots. ... It's kind of turned around our own ideas as to our roots. Up until this study, there has been an idea that we were pretty much forced out of the trees because we evolved in these open grasslands. That is a very common misperception.
[The Ardi investigation] really shows you that what we think of as a pretty unique human trait — bipedal locomotion — we didn't get pushed into this because we had to live in a grassland environment. We have to figure out another story.
Q: So we figure out how we came out of the trees — what do we learn from that?
A: If you take a look at the animal kingdom, how many animals are walking around on two legs? Obviously, understanding what caused us to do that gives us a better understanding of human beings. We're dominant on this planet. We've pretty much freed our hands to do things other than walking around on them ... and using our hands to manipulate objects like tools may have contributed to the expansion of the brain.